The notes document gives examples of evidence to provide.
You can also challenge a decision by calling the benefit office, however, it’s wise to have everything in writing.
You should try to ask for the reconsideration within one month of the date on your decision letter.
If you miss the deadline you can still ask for a mandatory reconsideration up to 13 months after receiving your letter.
However, you will have to explain your reasons for challenging late.